Treasury Secretary Steven Mnuchin said Thursday he wants to increase the level of U.S. trade but warned that measures will be taken where trade practices are deemed unfair.

"I would say the U.S. has the most open trading market in the world and the most open investment market in the world," Mnuchin said during a CNBC panel session at the World Economic Forum in Davos, Switzerland. "But we want fair trade we want reciprocal trade and where there are trade issues we will enforce them."

Numerous Davos attendees have pressed the United States this week to remain open to international trade and not use tariffs or other measures to bolster its domestic companies.

Mnuchin said the U.S. wants "more trade, not less trade" but that there were "big imbalances" where some markets were not fully open to U.S. companies.

Earlier this week, the Donald Trump administration's "America First" policy openly came into effect for the first time when tariffs were applied to imported solar panels and washing machines. The move was seen to have most affected Chinese and South Korean companies.

'Productive' talks with Chinese officials

Mnuchin said Thursday he had held "productive" talks with Chinese officials a day earlier about the imbalance in trade between the two countries. He added that Trump and President Xi Jinping were in agreement that the trade balance should fall.

"And that's about increasing exports to China to shrink that. We think it is one of the largest growing markets and we want U.S. companies to participate in an open way," Mnuchin said.

Speaking on the same panel, the Managing Director of the International Monetary Fund, Christine Lagarde, said "any measures that would restrict trade would hurt growth."

Lagarde said trade is a main engine of global growth and any effort to limit it would be worrisome.